A typical two-piece cup includes a sleeve forming the side wall of the container and a container bottom sealed with one end of the sleeve. One method for sealing the container bottom with the sleeve involves the use of a heat sealable material that is softened when heated and bonds two surfaces together when cooled and solidified. The container sleeve can include an end flange that is folded inward and overlaps with a portion of the container bottom to form the container bottom seal. The overlapping portion of the container bottom can be provided with a heat sealable material that can be softened by a suitable bottom heater prior to folding the sleeve end flange inward to overlap the sleeve with the container bottom. After the sleeve end flange is folded and overlapped with the container bottom, the heat sealable material can cool and solidify, bonding the overlapping portions together. The bottom heating process can affect the characteristics of the bottom seal. Too much heat can cause the heat sealable material to separate from the container surface and may damage parts of the cup. Not enough heat can result in insufficient softening of heat sealable material or not softening enough of the heat sealable material, which can lead to incomplete seal formation.